math
posted by gary .
A. Brad is 12 years older than Sam . If Brad were 8 years older than he is now. he would be twice as old as Sam. How old is Sam now?
B. Barrie is now 2 years older than Krista. In 15 years Barrie's age will be 2 years more than twice Krista's age now. How old will Barrie be in 6 years?
C. John is now 10 years older than Marcus. Three times John's age 5 years from now will be the same as five times Marcus's age 5 years ago. How old is John now?
D. In 1 year Kristen will be four times as old as Danielle. Ten years from then Kristen will only be twice as old as Danielle. How old is Kristen now?

A. 12+x+8=2x
20+x=2x
(subtract "x" from both sides)
x=20
B. x+2+15=2+2x
(subtract "2" from both sides)
x+15=2x
(subtract "x" from both sides)
x=15 (Krista's age)
15+2=17 (Barrie's age now)
17+6=23 
Phil is three times as old as Carrie. Five years ago, phil was four times as old as Carrie was at that time. How old is Carrie now?